Sphygmomanometer alarm reset technique

ABSTRACT

An alarm reset technique in a sphygmomanometer adapted for automatically monitoring a patient&#39;&#39;s blood pressure at regular intervals, having electronic detection circuitry responsive to an alarm condition defined by high- and/or low-alarm comparator units and other sphygmomanometer signals to activate an alarm, and electronic logic circuitry for resetting a prior interval activated alarm without inhibiting subsequent activation of the alarm in the interval when reset.

Guevrekian Jan. 25, T72

[54] SPHYGMOMANOMETER ALARM 3,536,062 10 1970 Horn ..128/2.05 R

RESET TECHNIQUE Primary Examiner-Wi|liam E. Kamm Inventor: Lawrence Guevreklan Kendall Attorney-Samuel L. Welt, Jon S. Saxe, Bernard S. Leon and Park, Jacob Frank 73 A si ne Hoffmann-La Rochell c. Nut] ,NJ. 1 s g e n CY 57 ABSTRACT [22] Filed: Jan. 12, 1970 An alarm reset technique in a sphygmomanometer adapted [21] AppLNo-i 2, 1 for automatically monitoring a patient's blood pressure at regular intervals, having electronic detection circuitry respon- [521 U S a] 128/2 05 A sive to an alarm condition defined by highand/or low-alarm [5]] comparator units and other sphygmomanometer Signals m av [58] Field of Search 128/2 05 A 2 05 M 2 05 R tivate an alarm, and electronic logic circuitry for resetting a d 5 6 prior interval activated alarm without inhibiting subsequent activation of the alarm in the interval when reset. [56] References Cited 7 Claims, 3 Drawing Figures UNITED STATES PATENTS 2,821,188 [/1958 Pigeon ..128/2.05 A

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I PROCESSING J UNIT RESET PULSE END PUMP UP HTG H ALAR M LO GIC 2nd PULSE R r 3 S I HIALCOMPlZ T; *?i r- T/ i l l PLE? f z kh I L. .J J I 4 I ALARM DEVICE L LL. L l v I i I R .v 4 S LOW AL.coMP ML: E |FTD PUMF-TI= I I I S A L 49 I f 7/- L vi i/ 3 I |L .J I i L ALARM DEVICE 3 I l Lw- L L L LJ PATENTEU JANZS 19?? SHEET 2 BF 2 A MEI "mull QNFCE] IQI I O9 09 OOm SPHYGMOMANOMETER ALARM RESET TECHNIQUE BACKGROUND OF THE INVENTION The present invention relates to an alarm system in a sphygmomanometer for monitoring maximum and/or minimum ac ceptable blood pressure values, and, more particularly an alarm reset for an automatic sphygmomanometer operation.

Automatic apparatus generally used for measuring blood pressure is known to play an important role in hospital, operating rooms, hospital intensive care wards, clinics and other medical facilities. Many of these devices are capable of providing for continuous patient monitoring to economize on vital nursing or attendant time by automatically monitoring a patients arterial pressure at regular intervals. This is generally accomplished by simple manipulation of a selector switch located on the front panel of the device enabling the operator to select a desired time span (e.g., 1,2,10, etc., minute inter vals). A visual and/or audible alarm is activated in instances where critical blood pressure pulses are detected at cuff pressure values which fall outside the acceptable blood pressure range defined by the preselected maximum and minimum values. During patient monitoring with such a multicycle device, it has been found expedient that an attending physician or nurse should be able to reset an activated alarm at any time without hampering the overall operation of the device. For example, an alarm reset operation should be feasible even while an alarm condition persists. Also, if the reset button is depressed prior to the occurrence of an alarm condition (i.e., during cuff inflation), the alarm should still be capable of being activated during the remainder of the interval or cycle, should an alarm condition then exist.

The purpose of the present invention is the provision of such an alarm reset arrangement for a preselected range of acceptable blood pressure values (having limits preset by the operator) in a sphygmomanometer capable of automatically monitoring a patients blood pressure at regular intervals. The above is accomplished by the utilization of alarm reset electronic logic allowing for alarm reset in a case, for example, where an alarm has been activated in response to an alarm condition during a preceding measurement interval, so that if the reset alarm button is depressed (following a measurement interval start pulse) prior to an alarm condition during an interval, a subsequent alarm in the same cycle will not be aborted, if detected. Thus the normal alarm operation is not inhibited. An additional object of the present invention permits quelling the alarm in a measurement interval while the alarm condition persists, should the reset button be depressed.

DESCRIPTION OF A PREFERRED EMBODIMENT Other objects, advantages, and capabilities of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.

In the drawings:

FlG. 1 is a schematic block diagram of the apparatus used in accordance with the invention;

FIG. 2 depicts a preferred embodiment of the invention by way of a detailed electrical logic diagram of the alarm logic 29 shown in FlG. 1;

FIG. 3 is a representative record of information which might be provided by the system.

Referring to FIG. 1, there is shown a blood pressure monitoring instrument 11, having on its front face a pair of manometer tubes 12 each having graduated pressure readings where the height of the mercury in the tube indicates the pressure level around the body limb 13 exerted by the cuff 14 which overlies the transducer assembly 15. Cuff 14 is supplied with air from an air pump (not shown) via conduit 16. Also on the instrument panel are: Power On, Start, and Alarm Reset buttons, and a multipositon Timing Switch for selecting convenient intervals for taking blood pressure measurements or readings. Selection of any of these periods causes the Start button which generates a start pulse to be automatically reset at the end of the specified interval, whereby an interval is measured between the time of two successive start pulses activa tions. l-lighand low-systolic alarm light indicators 17 and 13 respectively, also shown, are adapted to be illuminated when the patients detected systolic blood pressure is found to be above or below a given predetermined range of blood pressure values. Located alongside manometers 12 is a settable limit range indicator 19 for displaying, in direct relation to the manometersflhe preselected acceptable range of blood pressure values which, if exceeded in detecting the patients blood pressure, would cause an alarm condition to exist. The range of blood pressure values set is achieved. by manipulation of the movable alarm settings 21, 22.

The depicted highand low-alarm settings 21 and 22 might be connected to a potentiometer for providing electric signal alarm levels as shown in the common assigned copending U.S. Pat. application No. 737,940 filed June 18, 1968 for Monitoring Display by Ulrich A. Frank et al. now U. S. Patent No. 3,545,431. Electrical output signals corresponding to the highand low-preset levels 21 and 22, are coupled to highand low-alarm comparators 25 and 26 respectively, via lead wires 23 and 24. Each comparator is also provided with an electrical readout signal of the systolic manometer pressure level by connection via lead wire 27 from the systolic manometer tube.

The pulses picked up by transducer 15 and other electrical signals from the blood pressure monitoring instrument, are fed along lead wires connected to a control and processing unit 28 having its output coupled to an alarm logic unit 29, which is also coupled from the output side of high and low comparator units 25 and 26. Upon energization of the alarm logic unit to denote an alarm condition, the proper output alarm 17 or 18, and remote alarm 30 (of the visual and/or audible type) will be activated. When presence of the systolic pressure is detected by transducer 15 the mercury column in manometer tube 12 is arrested by conventional techniques such as use of a cutoff valve.

A detailed schematic diagram of alarm logic 29 is shown in FIG. 2, wherein an NAND-gate 32 is supplied with two inputs including the high-alarm comparator output, and an indication that the second blood pressure pulse signal has been detected by transducer 15. The second blood pressure pulse signal, which should follow within a prescribed time period after the first signal, is used in lieu of the first in order to ensure that the first signal was not merely noise. NAND-gate 33 is connected from the output of NAND-gate 32 and also from the Alarm Reset button which depressed provides an alarm reset pulse. The output of NAND -gate 33 is connected to the reset input of bistable of flip-flop circuit 34 comprising NAND-or NOR-gates 35, 36, the output of which is connected, along with the output of NAND-gate 32 and a Start button output (providing a start pulse when depressed), to NAND-gate 37. Also connected to the set input of flip-flop 34 is an output from the Start button. The output of NAND-gate 37 is connected to bistable or flip-flop circuit 33 comprising (NAND- or NOR-gates 39 and 41, the output of which is connected to a high-alarm device to provide upon given alarm conditions, an indication of a patients critical high-blood pressure which exceeds the predetermined limit 21. Bistable circuit 38 is also connected to the Alarm Reset button output via inverter unit 412.

In a similar fashion the low-alarm logic includes an NAN D- gate 43 supplied with a low-alarm comparator input, and end pumpup signal, and a start pulse from the Start button. NAND-gate 44 is connected from the output of NAND-gate 43 and from the Alarm Reset button, and is connected to bistable circuit or flip-flop 45 comprising NAND- or NOR- gates 46, 47 which bistable circuit set input is connected to the Start button. The outputs of NAND-gate 43, flip-flop 45 and the Start button, are each supplied to the input of NAND-gate 48 which output is connected to bistable circuit or flip-flop 49 including NAND-or NOR-gates 51 and 52. The output of flipflop 49 is connected to the low alarm device which is energized in the absence of detection of a blood pressure pulse signal by transducer 15, after cuff pressure has fallen below a critical blood pressure value at the predetermined limit 22.

OPERATION In operation of the present invention, with relation to FIGS. 1, l2, and 3, cuff 14 is first inflated about the patients limb from time 1-1, until time t-2 to attain a predetermined highcuft' pressure (e.g., 250 mm.) at which time cuff deflation takes place, and a conventional signal denoting the end of cuff inflation is generated. At time 2-3 the patients first one of the blood pressure pulses 53 is detected via transducer and systolic manometer tube 12 is arrested. Since at time t-3-the high-limit pressure reference value 21, shown in FIG. 1 is exceeded, the high-alarm comparator 25 is excited. Accordingly, at time 1-4, when the second blood pressure pulse is detected, gate 32 is enabled. Because a start pulse is generated at the commencement of each interval (here at time 1-1 gate 37 will also be enabled to trigger flip-flop 38 and thus set off the alarm device to denote that the patient has a critically high-systolic blood pressure. Unless the Alarm Reset button is depressed, the alarm will remain activated even during successive intervals such as that commencing at time t-7.

During the next measurement interval commencing at time 1-7 and prior to occurrence of a second blood pressure pulse detected at time :9, NAND-gate 32 is not enabled. Therefor, NAND-gates 33 and 37 are also disabled. If the attending physician now desires to reset the alarm, activated from the prior measurement interval, by depressing the Alarm Reset button, bistable circuit 38 is reset to deactivate the alarm. However, if alarm conditions were to exist at time t-9, a subsequent alarm in the same measurement interval t-7 to t-l2 will not be aborted.

Assuming that at t-9 alarm conditions exist to enable NAND-gate 32 the alarm device is activated. Should the Alarm Reset button then be depressed subsequent to time 29, for example, at time z-lO, NAND-gate 33 is enabled to reset bistable circuit 34 and thus disable NAND-gate 37. At the same time the Alarm Reset pulse is applied to bistable circuit 38 thereby turning off the alarm. Subsequent to this juncture, NAND-gate 37 can not be enabled even though alarm conditions were to persist in this interval, until commencement of a new interval (at time, e.g., t-l2) at which time a start pulse would trigger bistable circuit 34, thus inhibiting alarm activation during the remainder ofinterval t-7 to t-l 2.

Operation of the low-alarm logic would operate in a similar manner as the high alarm logic reviewed above. However, the alarm conditions in this instance would include the output of low alarm comparator 26 and a signal denoting end of pumpup or commencement of cuff deflation. These latter signals are expedient for detecting a systolic blood pressure falling below limit 22 on limit range indicator 19 for the reason that subsequent to time t-2, if manometer tube 12 is not arrested by detection of a systolic blood pressure pulse then the mercury level in the tube 12 will proceed to drop until it falls below the limit 22 to excite low-level comparator 26. Assuming the low-level alarm conditions to exist at time t- 6 NAND-gates 43 and 48 are enabled to activate the alarm display by triggering bistable circuit 49, then during the successive measurement interval between times t-7 and M 1, should the reset button be depressed, bistable circuit 49 is triggered to turn off the alarm activated from the preceding interval. Further, a subsequent alarm condition in interval 2-7 to t- 12 indicative of a low systolic blood pressure value below limit 22 in that same interval will not be aborted. Again, should the Reset button be depressed between times t-ll and 1-12, bistable circuit 49 is reset to turn off the alarm. Although the alarm conditions may persist at the output of Nand-gate 43, the alarm will not be activated again during that interval due to the disabling of NAND-gate 48.

Of course, even if the Alarm Reset button were to be accidentally depressed during an interval prior to an alarm condition with no prexisting alarm on, the detection and alarming of such a condition, during the same interval would be aborted.

I claim:

1. In an alarm system in a sphygmomanometer including a cufi' for applying external pressure about a patients limb during a blood pressure measurement cycle including cuff inflation and deflation, cuff pressure meter means, means associated with the cufi for detecting blood pressure pulses, reference pressure value setting means defining an acceptable range of systolic pressures, comparison means responsive to a comparison of the meter means pressure with said reference pressure values timing means for activating the measurement cycle at predetermined intervals, alarm means, logic means responsive to said comparison means and detecting means for defining an alarm condition to activate said alarm means, the improvement comprising:

reset means including a reset pulse to reset during a cuff pressurized portion of a measurement cycle, the alarm means activated from a prior interval, without inhibiting subsequent alarm means activation with occurrence of said alarm condition in the measurement cycle when reset.

2. In an alarm system according to claim 1 having a means providing a signal indicative of commencement of cuff deflation, and second logic means responsive to the comparison means and the signal to define a second alarm condition, and including:

second means to reset the alarm means activated from a prior interval, without inhibiting subsequent alarm means activation with occurrence of said second alarm condition in the measurement cycle when reset.

3. In an alarm system according to claim 1 wherein said logic means includes a first gate responsive to said alarm condition, and a first bistable means responsive to an output of the first gate to activate said alarm means, and

said reset means includes a second gate responsive to the reset pulse and the first gate output, and a second bistable means coupled with said first gate and responsive to the output of the second gate.

4. In an alarm system according to claim 3 wherein said second bistable means is coupled from said timing means, to be responsive at the commencement of each interval.

5. In an alarm system according to claim 2 wherein said second logic means includes a first gate responsive to the second alarm condition, and a first bistable means responsive to the output of said first gate to activate said alarm means, and

said second reset means includes a second gate responsive to said reset pulse and said first gate output, and a second bistable means coupled with said first gate and responsive to the output of the second gate.

6. In an alarm system according to claim 5 wherein said second bistable means is coupled from said timing means, to be responsive at the commencement of each interval.

7. In a method for alarm reset in a sphygmomanometer for automatically monitoring a patients blood pressure at regular intervals including the steps of applying pressure to a cuff encircling a patient LIMB,

detecting blood pressure pulses,

comprising preselected reference pressure values with the cuff pressure to define an acceptable range of systolic pressures,

generating a timing pulse with the commencement of each interval,

activating an alarm upon an alarm condition including detecting a blood pressure pulse occurring outside of the systolic pressure range, the improvement comprising resetting during a cuff pressurized portion of a measurement interval, the alarm from a prior interval without inhibiting subsequent activation of the alarm with occurrence of an alarm condition in the interval when reset. 

1. In an alarm system in a sphygmomanometer including a cuff for applying external pressure about a patient''s limb during a blood pressure measurement cycle including cuff inflation and deflation, cuff pressure meter means, means associated with the cuff for detecting blood pressure pulses, reference pressure value setting means defining an acceptable range of systolic pressures, comparison means responsive to a comparison of the meter means pressure with said reference pressure values timing means for activating the measurement cycle at predetermined intervals, alarm means, logic means responsive to said comparison means and detecting means for defining an alarm condition to activate said alarm means, the improvement comprising: reset means including a reset pulse to reset during a cuff pressurized portion of a measurement cycle, the alarm means activated from a prior interval, without inhibiting subsequent alarm means activation with occurrence of said alarm condition in the measurement cycle when reset.
 2. In an alarm system according to claim 1 having a means providing a signal indicative of commencement of cuff deflation, and second logic means responsive to the comparison means and the signal to define a second alarm condition, and including: second means to reset the alarm means activated from a prior interval, without inhibiting subsequent alarm means activation with occurrence of said second alarm condition in the measurement cycle when reset.
 3. In an alarm system according to claim 1 wherein said logic means includes a first gate responsive to said alarm condition, and a first bistable means responsive to an output of the first gate to activate said alarm means, and said reset means includes a second gate responsive to the reset pulse and the first gate output, and a second bistable means coupled with said first gate and responsive to the output of the second gate.
 4. In an alarm sysTem according to claim 3 wherein said second bistable means is coupled from said timing means, to be responsive at the commencement of each interval.
 5. In an alarm system according to claim 2 wherein said second logic means includes a first gate responsive to the second alarm condition, and a first bistable means responsive to the output of said first gate to activate said alarm means, and said second reset means includes a second gate responsive to said reset pulse and said first gate output, and a second bi-stable means coupled with said first gate and responsive to the output of the second gate.
 6. In an alarm system according to claim 5 wherein said second bistable means is coupled from said timing means, to be responsive at the commencement of each interval.
 7. In a method for alarm reset in a sphygmomanometer for automatically monitoring a patient''s blood pressure at regular intervals including the steps of applying pressure to a cuff encircling a patientlimb, detecting blood pressure pulses, comprising preselected reference pressure values with the cuff pressure to define an acceptable range of systolic pressures, generating a timing pulse with the commencement of each interval, activating an alarm upon an alarm condition including detecting a blood pressure pulse occurring outside of the systolic pressure range, the improvement comprising resetting during a cuff pressurized portion of a measurement interval, the alarm from a prior interval without inhibiting subsequent activation of the alarm with occurrence of an alarm condition in the interval when reset. 